This invention relates to signaling devices for trailer vehicles and more particularly to a novel angular direction or position sensor and indicator for alerting the vehicle operator to the angular displacement of the towing vehicle with respect to the towed load.
In the past, many situations have been encountered wherein the driver of a towing vehicle does not know the exact angular relationship of the towed load with respect to the towing vehicle. For example, it is frequently necessary to cause reverse movement of the trailer vehicle and the tow vehicle to move the trailer vehicle to a desired location. During the backing procedure, the towed load or trailer sometimes decreases the angular displacement between the vehicles and a condition known as "jack knife" is produced. Obviously, such a condition is undesirable and will cause damage to both trailer vehicles. Also, even when the towing vehicle is proceeding in a forward direction, it often happens that the trailer will fishtail causing unnecessary wear on the vehicles and particularly the tires. Again, this is a condition to be avoided.
Some attempts have been made to provide indicating devices for drawing the vehicle operator's attention to the fact that the trailing vehicle may be fishtailing or about to jack knife. Such prior attempts are disclosed in U.S. Pat. Nos. 3,605,088; 3,237,177 and 3,588,809. Although these devices have been operable for some of their objects, these devices do not indicate or display to the vehicle operator the direction of angular displacement during travel so that the operator can take corrective action. Also, these devices do not permit wide angular displacement up to 90.degree. and these devices are not entirely successful for indicating to the operator angular displacements during the reversing or backing procedures. Some of the prior art devices are extremely complex and require substantial alteration of either the towing vehicle or the trailing vehicle.
Therefore, there has been a long standing need to provide a simple sensing device and indicator system for displaying direction of angular displacement as well as actual angular position of a trailing vehicle with respect to the towing vehicle.